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Part III. Appendix 7: Biological Data ConsiderationsSPECIESThe basic units for biological data are species. The names of these species and descriptions of themare the products of individual scientists whose careers have been devoted to describing and understandingevolutionary relationships among species. Increasingly, such individuals take advantage ofDNA or RNA gene sequence data to differentiate among species and to trace their phylogeny. Eachspecies is the unique product of its evolutionary history. Species are classified according to theirevolutionary relationships using a well-established, internationally accepted hierarchical system ofnomenclature. New species are continually being described (Figure 1 in Grassle, 2000); the hierarchicaltree of evolutionary relationships among species and the associated nomenclature must continuallybe revised to incorporate new information. For this reason, biological data systems requiremore attention to metadata than do physical data systems.The names of each species of plant or animal are the key words for information about organisms.Although ideally each species is known by a single, unique name, in practice, a species maybe named more than once (creating synonyms) and the same name may be applied to more thanone species (creating homonyms). Therefore, biological data systems require name translators thatprovide accurate scientific names from synonymous and homonymous names. In addition, translatorsare needed to relate common names to their scientific counterparts. With oversight from theGlobal Biodiversity Information Facility (GBIF), Catalogue of Life, and organizations such as theIntegrated Taxonomic Information System (ITIS), Species 2000, and OBIS, the taxonomic authorityfor each major group of organisms maintains the accepted list of species.Biological specimens are stored in museums and/or are maintained in culture collections, dependingon the type of organism, to provide reference material for identification. Expert systems foridentifications are being developed; identifications, be they based on morphology, on DNA or RNAsequence data, or on some other sort of distinctive feature, use accepted species names. As a minimumquality control and quality assurance measure, the taxonomic authority (the name of theperson who originally described the species) and the name of the person identifying the specimenis typically included with each specimen record; such a practice is advisable for each data set basedon such a specimen.However, the units commonly used in biological oceanographic research are frequently not basedon species, but instead are based on habitat, taxa above the species level (genus, family, order, etc.),size, chlorophyll biomass, optical or acoustic signatures, and trophic position in food chains orfood webs. Such units are often used to quantify ecosystem function, and the precise identity ofthe component species is not considered germane to the question being studied. However, the relevanceof species-level information to the inference of ecosystem function of species assemblages290